Etchant composition, patterning conductive layer and manufacturing flat panel, display device using the same

ABSTRACT

An etchant composition that allows simplification and optimization of semiconductor manufacturing process is presented, along with a method of patterning a conductive layer using the etchant and a method of manufacturing a flat panel display using the etchant. The etchant includes nitric acid, phosphoric acid, acetic acid, and an acetate compound in addition to water.

This application claims the benefit of Korean Patent Application No.2008-0020352 filed in Korea on Mar. 05, 2008, which is herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an etchant composition, method ofpatterning a conductive layer, and manufacturing a flat panel displaydevice using the same. More particularly, the present invention relatesto an etchant composition for simultaneously etching aluminum,molybdenum, and aluminum alloy and methods of patterning a conductivelayer and manufacturing a flat panel display device using the same.

2. Description of the Related Art

In the prior art, an etchant that includes phosphoric acid, nitric acid,acetic acid and water is typically used to etch aluminum-basedconductive material. An additive could be added to the etchant. However,this conventional etchant has a number of disadvantages. First, becauseof irregular surface reaction, accurate and fine pattern of conductivematerial couldn't be formed. After 24 hours, the nitric acid portion inthe etchant shows a sharp fall in concentration, negatively affectingsurface uniformity. Furthermore, tip phenomenon occurs quite frequently.In a tip phenomenon, some part of a metal that is supposed to be etcheddoes not get. Due to these problems, productivity decreases.

If the etchant includes more than 5 weight % of nitric acid in thecomposition, tip phenomenon could be prevented. However, to produce anaccurate, fine pattern in the conductive layer, excessive etching of thelateral part of the conductive material is minimized. Too much nitricacid in the etchant causes damage to photo-resist and accelerateslateral etching.

Especially, in case of a multi-layer structure composed of differentconductive materials having different etching rates, the problem becomesmore serious because each layer may have to be etched by a differentetchant, the process for etching the multi-layer may use differentetching equipment for each layer, and the etching process for each layercan not be conducted at the same time. As a consequence, etching processgets complicated and manufacturing cost and time increases. Even if thesame etchant is used for etching the multi-layer structure, tipphenomenon could have due to different etching rate of each conductivematerial and galvanic effect, resulting in an etching quality that isnot sufficiently high. For the above reasons, there are many challengesto etching a multi-layer structure in an efficient manner (e.g., withthe same etchant for each layer).

These days, there is ever-increasing pressure to simplify and optimizemanufacturing processes and pattern uniformity. For example, TFT panelmanufacturing process has changed into 4 mask process from 5 maskprocess. Hence, it is a method of etching a multi-layer structureefficiently is desirable.

SUMMARY OF THE INVENTION

Accordingly, the present embodiment of invention is directed to acomposition of a etchant for removing conductive materials and amanufacturing method of an array substrate using the same thatsubstantially obviates one or more of the problems due to limitationsand disadvantages of the related art.

An advantage of the present embodiment of invention is to provide anetchant composition capable of simplifying an etching process andminimizing manufacturing costs, and increasing productivity, and methodsof patterning a conductive layer and manufacturing a flat panel displaydevice using the same.

Additional features and advantages of the embodiment of invention willbe set forth in the description which follows, and in part will beapparent from the description, or may be learned by practice of theinvention. The objectives and other advantages of the invention will berealized and attained by the composition and method particularly pointedout in the written description and claims hereof as well as the appendeddrawings.

To achieve these and other advantages and in accordance with the purposeof the present embodiment of invention, as embodied and broadlydescribed, an etchant composition includes a phosphoric acid, a nitricacid, an acetic acid, water and an additive, wherein the additiveincludes acetate compound.

In another aspect of the present invention, a method of patterning aconductive layer: providing a substrate; forming a conductive layer onthe substrate, wherein the conductive layer is a single layer formed ofat least one of Al, Al alloy, and Mo, or a multilayer thereof; forming aphotoresist layer on the conductive layer; patterning the photoresistlayer by photo exposure; and etching the conductive layer using thepatterned photoresist layer as an etch mask, wherein an etchantcomposition used to etch the conductive layer includes a phosphoricacid, a nitric acid, an acetic acid, water and an additive, wherein theadditive includes acetate compound.

In another aspect of the present invention, a method of manufacturing aflat panel display device includes : providing a substrate; forming afirst conductive layer on the substrate; patterning the first conductivelayer to form a gate electrode; form-ting a gate insulating layer on thegate electrode; forming a semiconductor layer on the gate insulatinglayer corresponding to the gate electrode; forming a second conductivelayer on the semiconductor layer; patterning the second conductive layerto form source drain electrodes; forming a passivation layer to beelectrically connected to the drain electrode through the contact hole;and patterning the third conductive layer to form a pixel electrode,wherein the gate electrode, the source/drain electrodes and the pixelelectrode are patterned by using one same etchant composition.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a scanning electron microscope (SEM) photograph illustrating across-section of multilayer of Mo/Al wet etched by an etchant.

FIG. 2 is a scanning electron microscope (SEM) photograph illustrating across-section of multilayer of Mo/Al/Mo wet etched by an etchant.

FIG. 3 is a scanning electron microscope (SEM) photograph illustrating across-section of multilayer of Mo/Al/Mo wet etched by an etchantincluding more than 10 weight % of nitric acid.

FIG. 4 is a scanning electron microscope (SEM) photograph illustrating across-section of single layer wet etched by an etchant including morethan 7 weight % of nitric acid.

FIG. 5 is a scanning electron microscope (SEM) photograph illustrating across-section of layer of Mo/Al/Mo wet etched by an etchant withoutacetate compound.

FIG. 6 is a scanning electron microscope (SEM) photograph illustrating across-section of layer of Mo/Al/Mo wet etched by and etchant includingabout 1 weight % of nitric acid.

FIGS. 7, 8, and 9 are cross sectional views illustrating a method ofpatterning a conductive layer using an etchant composition according toan embodiment of the present invention.

FIGS. 10, 11, and 12 are cross sectional views illustrating a method ofmanufacturing a flat panel display device according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthrough out the drawings to refer to the same or similar parts.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. In contrast, when anelement is referred to as being “directly on,” “directly connected to”or “directly coupled to” another element or layer, there are nointervening elements or layers present.

The embodiments of the present invention will be more fully illustratedthrough experimental examples and comparative examples. The experimentalexamples below are exemplified for illustrative purpose so that thepresent invention is not limited to these examples.

The etchant composition of the invention can be used in etching aconductive structure. The conductive structure could be eithermono-layer or multi-layer. A monolayer structure could be formed by ametal which is selected from molybdenum, aluminum, and aluminum alloy.The multi-layer structure could be formed with the above metals.

During an etching process, a chemical is provided on to the surface of amaterial to be etched. Material on the surface reacts with the chemical,and a soluble product is produced from the reaction. If this solubleproduct is taken out from the surface, a pattern is formed.

Now, the chemicals and their proper weight percent in the etchant willbe explained.

The etchant includes phosphoric acid, nitric acid, acetic acid, water,and acetate compound. Proper weight percent of phosphoric acid is fromabout 50 weight % to about 77 weight percent. In case of nitric acid,proper weight percent is from about 2 weight % to about 5 weight %.Proper weight percent of acetic acid is from about 1 weight % to about25 weight percent. And in case of acetate compound, proper percentage ofacetate compound is from about 1 weight percent to about 10 weightpercent. The remainder of the composition could be water.

Nitric acid reacts with aluminum to form oxide. About 2 weight percentto about 5 weight percent of nitric acid disclosed in this inventionwill be effective to control the selectivity in etching a multi-layerstructure composed of different metals. When the content of the nitricacid is within the above-disclosed range, the nitric acid effectivelycontrols the etching selectivity between an upper layer and a lowerlayer of the multi-layer structure.

Phosphoric acid plays a role in decomposing the aluminum oxide. About 50weight percent to about 77 weight percent phosphoric acid will help toenhance the etching speed rapidly by decomposing the aluminum oxideeffectively.

At this time, acetic acid and water is used to dilute the etchant.Acetic acid is also useful for controlling the speed of oxidationreaction. Generally, excessively fast decomposing speed will reduce theremaining time of a proper profile. Thus, proper composition of aceticacid and water is important in the etching process.

Acetate compound is formed by transforming a hydrogen ion of acetic acidinto metal ion such as sodium ion, potassium ion, calcium ion andaluminum ion. And hydrogen ion of the acetic acid can be transformed byammonium ion also. Most of acetate compound is dissolved into water anddissociated into metal ion and acetic ion. Generally, the chemicalformula for an acetate salt is M^(n) (CH₃COO)_(n) (wherein M is a metal.Sodium acetate and calcium acetate are salts that have this chemicalformula. Chemical formula for an acidic salt is M^(n)(CH₃COO)_(n).m(CH₃COOH). Chemical formula for a basic salt isM^(III)(OH)(CH₃COO)₂ (M^(III):AlGa) and M^(III)O(CH₃COO). The acetatecompound controls the etching rate to minimize lateral etching of theconductive layer and the decomposition rate of nitric acid in theetchant to achieve a good profile of the metal layer's pattern.

Phosphoric acid, nitric acid, and water used in semiconductor processmeet a requisite level of purity. In case of water, de-ionized water isused. If an etchant has a composition of the invention described herein,the amount of lateral etch can be minimized. Reducing the amount oflateral etch is a critical factor for fine patterning, and the inventionallows a good control over the lateral etch to achieve this goal.

If phosphoric acid makes up over 77 weight percent of the etchant, thehigh viscosity of phosphoric acid will damage the etching equipment. Forexample, the sprayer that is used for spraying the phosphoric acid maynot work well. On the other hand, if phosphoric acid makes up less than55 weight percent of the etchant, it may not decompose the oxide onsurface enough, and therefore fail to achieve the intended etchingprofile. For these reasons, phosphoric acid between about 55 weightpercent and about 77 weight percent is preferable.

If nitric acid makes up over 5 weight percent of the etchant, it maydamage the photo-resist layer, making it difficult to obtain theintended photo-resist pattern. Also, it results in excessive lateraletch of the conductive layer and cause electrical signal line open. Onthe other hand, if nitric acid makes up less than 2 weight percent ofthe etchant, it may not properly form the oxide layer on the surface ofthe metal to be etched, making it difficult to pattern the conductivelayer.

If acetic acid makes up over 25 weight percent of the etchant, itdestroys the photo-resist layer and interferes with the formation of thedesired photo-resist pattern.

The acetate compound makes up between about 1 weight percent and about10 weight percent of the etchant. If the acetate compound makes up over10 weight percent of the etchant, it may cause problems due to highviscosity or excessive reduction in the etching rate. On the other hand,if the acetate compound makes up less than 1 weight percent, it may notsufficiently control the etching rate. Nitric acid is not only anoxidizing agent but also a weakening agent of the adhesiveness betweenthe photo-resist and metal layer to be etched. The acetate compoundcontrols the rate of oxidation-reduction reaction and prevents excessiveweakening of the photo-resist adhesiveness. Further, it helps to preventexcessive lateral etching. That is to say, using the acetate compoundwithin the range disclosed herein to control the etching rate willresult in minimum of lateral etching and good patterning of metal layer.Moreover, because the acetate compound lowers the volatility of nitricacid, it can increase a life time of the etchant.

EXPERIMENTAL EXAMPLE

In this embodiment, a glass substrate having a width of 100 mm andlength of 100 mm is used. Three metal structures are compared: a firststructure that includes a molybdenum monolayer, a second structureincluding a molybdenum/aluminum bilayer, and a third structure includinga molybdenum/aluminum/molybdenum triple layer.

TABLE 1 Layer Mo Mo/Al Mo/Al/Mo thickness 2500 Å 500/2500 Å1000/2000/500 Å

According to Table 1, the Mo mono layer is formed on the substrate witha thickness of 2500 Å. The Mo/Al bilayer is formed sequentially on thesubstrate with a respective thickness of 500 Å/2500 Å. In the particularexample, the Mo layer is formed on the Al layer. In case of Mo/Al/Motriple layer, the total thickness is 3500 Å. The aluminum layer in thisembodiment of the invention can be either pure aluminum or an alloy.

Experiment 1-6

Fifteen kg of an etchant including phosphoric acid, nitric acid, aceticacid, acetate compound (KCH3COO, NH2CH3COO), and water is used. Theetchant is provided into a spraying-type etching equipment. Temperaturewas maintained at 40±0.5 degrees Celsius. Etching method was sprayingtype, which sprays the etchant on the substrate. Etching time was overetch (O/E) 50% and 70% with a standard of EPD (End Point Detection).After completing etching, cleaning and drying process was conducted.With SEM, we checked the amount of lateral etching, taper angle, damageof photo-resist, and residue of etchant. The standard for evaluating isas follows: If the CD skew is below 0.5 μm when the over etching rate is70%, the overall etch is regarded as Excellent; if The CD skew isbetween 0.5 μm and 0.6 μm, it is regarded as Good. The Tip phenomenonfor the Mo layer on the top or the bottom layer have to be less than0.03 μm in both of these cases. If the overall etch is evaluated asFail, it means it doesn't have proper composition. If the composition isnot evaluated as Excellent or Good, it is regarded as Fail. The CD skewrefers to the difference between the width of the pattern after thephoto-process, before etching and the width of actual pattern afteretching. If the difference is large, it means the amount of lateral etchis big.

TABLE 2 Composition ratio (wt %) CD skew (μm) Taper Angle, ° No. ofAcetate (phosphoric acid/nitric acid/acetic O/E O/E O/E O/E ExperimentMetal layer compound acid/acetate compound/DIW) 50% 70% 50% 70%Evaluation 1 Mo CH3COOK 65/3.5/15.5/2.5/13.5 no damage of PR 2 Mo/Al0.34 0.41 70.51 73.65 Excellence 3 Mo/Al/Mo 0.34 0.47 63.43 70.5Excellence 4 53/4/13/3.5/27 0.38 0.56 61.86 59.66 Good 5 70/4/6/3.5/170.4 0.5 69.54 73.3 6 CH3COONH4 73/5/6.7/1/14.27 0.40 0.56 62.45 67.75 7Mo/Al 0.41 0.54 62.65 72.72

Comparative Experiment 1-4

After preparing 15 kg of etchant including phosphoric acid, nitric acid,acetic acid, acetate compound (KCH₃COO) and water, we evaluate theresult of etching.

TABLE 3 CD skew Composition ratio (wt %) (μm) (Taper Angle, °) No. ofAcetate (phosphoric acid/nitric acid/acetic O/E O/E O/E O/E ExperimentMetal layer compound acid/acetate compound/DIW) 50% 70% 50% 70%Evaluation 1 Mo CH3COOK 33/10/13/3/41 Damage of Photoresist fail 2Mo/Al/Mo cannot etch fail 3 63/7/13/3.7/14 0.66 0.88 58.09 52.21 fail 4CH3COONH4 63.71/4.2/10.13/0/17.96 0.84 1.02 24.12 29.25 fail 563/1/13/3/20 0.38 0.52 50.08 56.31 fail

FIG. 1 is a scanning electron microscope (SEM) photographs illustratinga cross-section of multilayer of Mo/Al wet etched by an etchant.

FIG. 1 shows the result of embodiment 2 of table 2. The metal layer inthis embodiment was molybdenum(20)/aluminum(10) bilayer. The compositionof the etchant was 65 weight percent phosphoric acid, 3.5 weight percentnitric acid, 15.5 weight percent acetic acid, 2.5 weight percent acetateacid, and 13.5 weight percent water. The acetate compound used in thisembodiment is potassium acetic acid (CH₃COOK). The CD skew (amount oflateral etching) is the difference between the line width before etchingand the line width after etching. When the over-etching rate is 50percent, CD skew is 0.34 μm. When the over etching rate is 70 percent,CD skew is 0.47 μm. Comparing to embodiment 3 of table 3, there isdifference in the amount of phosphoric acid; in embodiment 3, phosphoricacid makes up only 33 weight percent of the etchant. In embodiment 3,however, the photo-resist was damaged and it was impossible to etch forpatterning. This is because less than 50 weight percent of phosphoricacid couldn't decompose the oxide surface sufficiently well. This resultis Excellent by a evaluation standard. Beside, Tip phenomenon of top Molayer (20) is not observed, and the taper angle is 73.65 degree. Thus,the etchant composition disclosed in this embodiment of the inventionyielded superior etching result which makes possible to make a finepattern.

FIGS. 2 is a scanning electron microscope (SEM) photograph illustratinga cross-section of a Mo/Al/Mo structure wet etched by an etchant. Theetch result is that of embodiment 3 of table 2. Molybdenum and aluminumlayers are formed on the substrate sequentially. The composition of theetchant is 65 weight percent phosphoric acid, 3.5 weight percent nitricacid, 15.5 weight percent acetic acid, 2.5 weight percent acetate acid,and 13.5 weight percent water. Acetate compound used in this embodimentis potassium acetic acid (CH₃COOK). This embodiment was controlled undersame condition like the embodiment 2. When over etching rate is 50percent, CD skew is 0.34 μm. When over etching rate is 70 percent, CDskew is 0.41 μm. 0.34 CD skew is enough to make a fine pattern. Thiscomposition is evaluated as Excellent. And the Tip phenomenon of Molayer (20,30) is less than 0.03 μm. Thus, this composition within arange disclosed in this embodiment of the invention is enough to make anaccurate and fine pattern of conductive layer.

FIG. 3 is a scanning electron microscope (SEM) photograph illustrating across-section of Mo mono-layer wet etched by an etchant including morethan 10 weight % of nitric acid. As we can observe through the figure,the photoresist (50) itself was damaged, so the pattern couldn't beformed at all. This figure shows the result yielded by using an etchantincluding more than 10 weight % of nitric acid. This figure is enough toprove that etchant including more than 5 weight percent of nitric acidis not suitable for etching.

FIG. 4 is a scanning electron microscope (SEM) photograph illustrating across-section of single conductive layer wet etched by an etchantincluding more than 7 weight % of nitric acid. The result is on thecomparative experiment 3 in Table 3. The target layer is Mo/Al/Mo layer.The acetate compound was CH₃COOK. The composition of phosphoric acid,nitric acid, acetic acid and water was 63, 7, 3.7, and 14 weight %,respectively. When the over etch rate was 70%, CD skew was 0.88 μm,which was beyond the standard. This is because too much nitric acidcomposition in the etchant caused difficulty in controlling the etchingrate and increased CD skew.

FIG. 5 is a scanning electron microscope (SEM) photograph illustrating across-section of a Mo/Al/Mo structure wet etched by an etchant withoutan acetate compound. The result is shown on the compared experiment 4 inTable 3. In this experiment, the etchant didn't include an acetatecompound at all. If the etchant doesn't include the acetate compound, itbecomes too difficult to control the decomposing rate of nitric acid.Accordingly, excessive lateral etch happens, which results in 1.02 μm in70% over etch. Absence of acetate compound results in failure ofcontrolling of etching rate. This result shows that the acetate compoundin the etchant composition as an essential component.

FIG. 6 is a scanning electron microscope (SEM) photograph illustrating across-section of layer of Mo/Al/Mo wet etched by and etchant includingabout 1 weight % of nitric acid. The result satisfies the evaluationstandard. But as we can observe from the figure, Mo layer on thealuminum layer is not etched enough, which results in Tip phenomenon.The nitric acid is less than 1 weight percent. In this composition,oxidation layer can't be formed enough to form the desired pattern.Based on this experiment it has been determined that the minimum nitricacid composition to achieve the fine pattern is about 2 weight percent.

FIGS. 7, 8 and 9 are cross-sectional views illustrating a method ofpatterning a conductive layer using the etchant composition according toan embodiment of the present invention.

Referring to FIG. 7, a substrate (100) is provided. A conductive layer(200) is formed on the substrate. The conductive layer may be a singlelayer formed of at least one of aluminum (Al), molybdenum (Mo), and analuminum alloy containing at least one of Nd (Neodymium), Ni (Nickel),Nb (Niobium), or a multilayer structure of these layers.

A photoresist layer may be formed on the conductive layer (200).Subsequently, an exposure mask (not shown) is aligned over thephotoresist layer. The exposure mask has a predetermined shapecorresponding to the pattern of a conductive pattern. Then, ultravioletlight is irradiated on the exposure mask. Then, the photoresist layer ispatterned into the shape of the exposure mask. The photoresist layer maybe a negative photoresist layer through which a non-irradiated portionis removed, or a positive photoresist layer through which an irradiatedportion is removed. The substrate is dipped into a developer solutionthereby forming a photoresist pattern (300) exposing a portion of theconductive layer.

Referring to FIG. 8, the exposed conductive layer by the photoresistpattern (300) is etched using an etchant so as to form a conductivepattern. The etchant composition includes a nitric acid of about 2weight % to about 5 weight %; a phosphoric acid of about 50 weight % toabout 77 weight %; an acetic acid of about 1 weight % to about 25 weight%; an acetate compound of about 1 weight % to about 10 weight %; andwater of residual quantity.

Thereafter, as illustrated in FIG. 9, the photoresist pattern (300) isremoved so that the conductive pattern (200′) remains on the substrate.

FIGS. 10, 11 and 12 are cross-sectional views illustrating a method ofmanufacturing a flat panel display device according to an embodiment ofthe present invention.

Referring to FIG. 10, a substrate (100) is prepared. The substrate maybe formed of plastic, glass, or metal. A first conductive layer isformed on the substrate. The first conductive layer is patterned into apredetermined configuration to thereby form a gate interconnection (notshown) and a gate electrode. The first conductive layer may be a singlelayer formed of at least one of aluminum (Al), molybdenum (Mo), and analuminum alloy containing at least one of Nd (Neodymium), Ni (Nickel),Nb (Niobium), or a multilayer structure containing the above. The gateinterconnection and the gate electrode may be formed as a bilayer ortriple layer structure in which the Mo layer and Al layer are stacked.

Referring to FIG. 11, a gate insulating layer (120) is formed on thegate interconnection and the gate electrode, wherein the gate insulatinglayer is formed of a silicon layer, a silicon nitride layer, ormultilayer thereof. The gate insulating layer may be formed usingchemical vapor deposition (CVD) or a sputtering process. For instance,the CVD process may be performed using at least one of low pressure CVD(LPCVD), atmospheric pressure CVD (APCVD), and plasma enhanced CVD(PECVD).

Thereafter, an active layer (131) and an ohmic layer (132) are stackedon the gate insulating layer (120) corresponding to the gate electrodeso as to form a semiconductor layer configured with the active layer(131) and the ohmic layer (132). Herein, the active layer may be formedof amorphous silicon, and the ohmic contact layer may be formed ofamorphous silicon doped with n-type or p-type impurities.

After a second conductive layer is formed on the semiconductor layer, itis patterned into a predetermined shape to thereby form a datainterconnection (not shown) and source/ drain electrodes (140). Herein,the second conductive layer may be a single layer formed of at least oneof aluminum (Al), molybdenum (Mo), and an aluminum alloy containing atleast one of Nd, Ni, Nb, or a multilayer structure including the above.The data interconnection and the source/drain electrodes may be formedof a Mo single layer.

Accordingly, a thin film transistor, configured with the gate electrode(110), the source/drain electrodes (140), and the semiconductor layer(130) is completed.

Referring to FIG. 12, a passivation layer (150) is formed on the datainterconnection and the source/drain electrodes. Thereafter, a contacthole (CNT) is formed so as to expose a portion of the drain electrode.Herein, the passivation layer may be formed of silicon nitride, siliconoxide, and acryl-based compound.

Afterwards, a third conductive layer is formed on the passivation layersuch that it is electrically connected to the drain electrode throughthe contact hole. Subsequently, the third conductive layer is patternedinto a predetermined shape thereby forming a pixel electrode (160). Thepixel electrode (160) may be formed of a transparent electrode, e.g.,ITO or IZO.

Each of the gate electrode, the source/drain electrodes, and the pixelelectrode may be patterned using the same etchant composition. Theetchant composition may include a nitric acid of about 2 weight % toabout 5 weight %; a phosphoric acid of about 50 weight % to about 77weight %; an acetic acid of about 1 weight % to about 25 weight %; anacetate compound of about lweight % to about 10 weight %; and water ofresidual quantity.

Although a method of manufacturing a bottom gate type TFT isillustrated, the present invention, including the etchant composition,may be used to manufacture another type TFT such as a top gate type TFTor the like.

Thereafter, a flat panel display device may be fabricated according towell-known processes. For instance, if the flat panel display device isa liquid crystal display device (LCD), a liquid crystal is injectedbetween a first substrate in which a color filter and a transparentelectrode are disposed and a second substrate in which the TFT isformed, to thereby manufacture the LCD.

If the flat panel display device is an organic electroluminescencedisplay device (OLED), another electrode is formed on an organic layerafter forming the organic layer to include a luminescent layer on thepixel electrode, to thereby manufacture the OLED. Herein, the organiclayer may further include a charge transport layer or a charge injectionlayer.

Therefore, even if the gate interconnection and gate electrode, the datainterconnection and source/drain electrodes, and the pixel electrode areformed of different materials, they may be patterned using the sameetchant composition. Therefore, processes may be simplified so that itis easy to manufacture the flat panel display device.

According to the present invention, because the etchant composition iscapable of simultaneously etching aluminum, molybdenum, and ITO, all ofthe gate electrode, the source/drain electrodes, and the pixel electrodemay be formed using the same etchant so that it is easy to controlprocessing.

In addition, etching processes may be simplified so that it is possibleto enhance productivity and reduce manufacturing costs.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A composition of etchant, comprising; nitric acid of about 2 weight %to about 5 weight %; phosphoric acid of about 50 weight % to about 77weight %; acetic acid of about 1 weight % to about 25 weight %; acetatecompound of about 1 weight % to about 10 weight %; and water of residualquantity.
 2. The composition according to claim 1, wherein the acetatecompound includes at least one anion of sodium(Na), potassium(K),ammonia(NH3), calcium(Ca), and aluminum(Al).
 3. The compositionaccording to claim 1, wherein the acetate compound is an acid salt.
 4. Amethod of patterning a conductive layer, the method comprising; forminga first conductive layer on a substrate, wherein the conductive layerincludes at least one of Al, Al alloy, and Mo; patterning a photoresistlayer by photo-exposure; and etching the conductive layer using thepatterned photoresist layer as an etch mask; wherein an etchantcomposition used to etch the conductive layer includes a phosphoricacid, a nitric acid, an acetic acid, an acetate compound, and water. 5.The method according to claim 4, wherein the composition includes nitricacid of about 2 weight % to about 5 weight %; phosphoric acid of about50 weight % to about 77 weight %; acetic acid of about 1 weight % toabout 25 weight %; an acetate compound of about 1 weight % to about 10weight %; and water of residual quantity.
 6. The method according toclaim 5, wherein the acetate compound includes at least one of anion ofsodium (Na), potassium (K), ammonia (NH3), calcium (Ca), aluminum (Al).7. The method according to claim 5, wherein the acetate compound is anacid salt.
 8. A method of manufacturing a flat panel display device, themethod comprising; providing a substrate; forming a first conductivelayer on the substrate; patterning the first conductive layer to form agate line and a gate electrode; forming a semiconductor layer on thesubstrate corresponding to the gate electrode; forming a secondconductive layer on the semiconductor layer; patterning the secondconductive layer to form source/drain electrodes; wherein the gateelectrode and the source/drain electrodes are patterned using oneetchant composition including phosphoric acid, a nitric acid, an aceticacid, an acetate compound, and water.
 9. The method according to claim8, wherein the composition including a nitric acid of about 2 weight %to about 5 weight %; a phosphoric acid of about 50 weight % to about 77weight %; an acetic acid of about 1 weight % to about 25 weight %; anacetate compound of about 1 weight % to about 10 weight %; and water ofresidual quantity.
 10. The method according to claim
 9. wherein theacetate compound inclijde,q at least one of anion of sodium (Na),potassium (K), ammonia (NH3), calcium (Ca), aluminum (Al).
 11. Themethod according to claim 10, wherein the acetate compound is an acidsalt.